Magnetic Resonance Imaging and Fibrosis: Histological and Functional Changes in Left Ventricular Function Caused by Aortic Valve Disease

AORTIC VALVE DISEASE & VENTRICULAR FUNCTION Aortic valve disease is the most common valvular heart disease in Europe (46.4%). The valve can be stenotic (aortic stenosis, AS) or can leak (aortic regurgitation, AR). While mostly elderly patients suffer from AS (a steadily growing group due to the increasing population above 60 years), AR occurs in younger individuals (20-60 years in general) who are still working and have a long life expectancy. The current treatment is aortic valve replacement (AVR) and in Sweden approx. 1800 AVR are performed every year with an increasing tendency. AVR is a procedure with low mortality (1.7%) nevertheless there is limited information available about postoperative morbidity, physical performance and quality of life.

Present guidelines suggest surgery when patients are presented with symptoms and/or show impairment of LVF (increasing LV diameters, declining ejection fraction - EF). These are though fairly crude measures as both symptoms and LV dilatation occur late in the natural history of the disease. Furthermore, we found previously that symptoms and LVF did not correlate which warrants the quest for searching more precise indicators.

AS causes pressure and AR causes volume overload which the LV compensates by concentric or eccentric hypertrophy initially. As the disease progresses even histological changes present e.g. diffuse fibrosis. Regional fibrosis after myocardial infarction is known to cause impaired LVF. However, there is no information available in the medical literature on how diffuse myocardial fibrosis affects LVF and whether it would be reversible following prosthetic valve implantation.

Cardiac surgery always carries risks for complications (e.g. mortality, stroke, postoperative arrhythmias, infections etc.) and life with a prosthetic heart valve is not necessarily uncomplicated. Our previous studies showed that preoperative impairment of the LVF can be irreversible and, as Gjertson showed, can progress to heart failure despite operation. Postoperative heart failure has a profound impact on long-term prognosis.

FIBROSIS & CARDIAC MAGNETIC RESONANCE IMAGING (cMRI) Well defined ischemic scars visualized reliably on cMRI by late gadolinium enhancement making it a useful diagnostic modality for myocardial viability in the clinical practice. Currently, in-vivo information on diffuse myocardial fibrosis is limited and optimal imaging method for clinical use is not established yet.